Traditionally, the head portion is 30 feet long. That makes changing lines easy. All you do is coil the head around your hand, pass it through a 6- to 8-inch loop in the running line, secure it with something like a pipe cleaner, grab a different head and interlock it with the running line loop. Basing recommended line weights on full-length weight-forward lines, the standard practice is to increase line shooting head weights typically by two line sizes. Thus, an appropriate shooting head for an 8-weight rod would be one with a 10-weight designation. For a 10-weight rod, use a 12-weight shooting head. For those who prefer to select their lines by grain weight, the following is a useful guide: For an 8-weight fly rod, the head should weigh approximately 300 grains, a 9-weight rod will handle 350 grains, a 10-weight rod 400 grains, an 11-weight 450 grains and a 12-weight 500 grains.